The New Connection Between Depression and Chronic Inflammation

The prevailing notion in the psychiatric community is that depression is caused by an imbalance of “feel good” chemicals in the brain, neurotransmitters like serotonin and norepinephrine. Recent studies, however, are challenging this idea and pointing to a different and far more surprising culprit that may be the cause: our own immune system. These discoveries could have revolutionary implications for the treatment, prevention and cure of depression.

A 2015 study found that depressed people had a 30% higher rate of inflammation in their brains

Depression exacts a heavy toll in the US with one in eight Americans taking antidepressant medications, yet at least 1/3 of patients don’t respond to the existing treatments. In an attempt to make therapeutic advances, scientists have begun exploring the new frontier that connects immunity, inflammation and depression.

Anyone who has had a viral or bacterial infection knows what it means to feel sick. Our behavior changes dramatically. We lose interest in our daily activities, feel less sociable, suffer from fragmented sleep, and generally feel lethargic, despondent, groggy and irritable. In other words, we begin to exhibit the symptoms of depression. This “sickness behavior” has previously been passed off as just symptoms of being sick.

The Role of Pro-Inflammatory Cytokines

The discovery of substances known as pro-inflammatory cytokines is now shifting our understanding of sickness behavior. Recent research found that these substances that are produced at the site of an infection to coordinate the local response to pathogens also move through the system and act on the brain to produce the behavioral symptoms of sickness. This adaptive response helps us to better cope with an infection or injury. This same study also found that the pro-inflammatory cytokines spark depression in some patients with no previous history of mental disorders.

This normal inflammatory response usually lasts a few hours or days and then recedes when the threat is gone. But sometimes inflammation can go rogue and continue to proliferate for weeks, months, or even years. This is called chronic inflammation, during which the immune system turns on the body by attacking healthy cells, blood vessels and tissues instead of protecting them. Chronic inflammation has been linked to many of the leading causes of death in the United States, including heart disease, cancer, diabetes, stroke, Alzheimer’s disease, kidney disease, and chronic lower respiratory disease. Recent studies have even suggested that markers of chronic inflammation, such as C-Reactive Protein (CRP), can predict the incidence of death due to all causes as well as the incidence of death due to circulatory diseases and cancer.

Chronic Inflammation and the Brain

Chronic inflammation can occur anywhere in the body, and new evidence shows that this includes the brain. Several recent research findings support that chronic brain inflammation may be responsible for a host of brain-related problems, including depression. A large study published in 2016 revealed that peripheral markers of inflammation are frequently found in depressed individuals. The researchers examined data from 14,275 people, some who had depression and some who did not, and found that those who were depressed had 46% higher levels of CRP, the marker of inflammation, in their blood samples. Besides having increased inflammation in their bodies, a 2015 study found that depressed people had a 30% higher rate of inflammation in their brains with the most severely depressed having the highest brain inflammation rates of all.

We are certain to see a new wave of pharmaceutical treatments developed. A 2013 study of depressed patients with high baseline inflammatory biomarkers saw an improvement in their symptoms after they took a medication used to treat inflammatory diseases.

Effective Lifestyle Changes

Fortunately, there are other ways besides, or in addition to drugs, to combat chronic inflammation in order to manage depression. Making some basic lifestyle changes can be very effective, because chronic inflammation is largely caused by unhealthy lifestyle habits, such as lack of exercise, chronic stress, alcohol abuse, poor diet, and isolation/loneliness.

Here are five anti-inflammatory lifestyle tips that will help quell inflammation in the brain.

1. Go for a brisk walk each day. Aim for 30 minutes. If you can’t do 30 minutes, it’s OK to break it up into two 15 minute or three 10 minute walks. Interestingly, moderate exercise is actually better than strenuous exercise which can increase inflammation.
2. Adopt a regular stress management routine that includes such practices as gentle yoga and meditation. Also, get adequate sleep.
3. Avoid alcohol or limit consumption to one serving per day, which is 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of distilled liquor.
4. Eat an anti-inflammatory diet. Here are a few tips to promote an anti-inflammatory environment in your body.
5. Give and receive more love and support in your life. Go here to find some ways to enhance your social connections.

All of these tips are part of the guidelines for Ornish Lifestyle Medicine. Our research has shown that after just 12 weeks in the Ornish Lifestyle Medicine program, we see improvement in inflammatory markers like CRP, and 73% of participants who started with depressive symptoms stopped feeling depressed, with both men and women showing similar improvements in depression.

There are no side effects to following these lifestyle medicine guidelines except good ones. You are likely to experience a reduction in other inflammatory conditions.

How have lifestyle changes had an impact on your mental and physical health?